Support MeSH

[stefandesu]

Mappings to MeSH can already be loaded and are shown correctly in Cocoda (at least the descriptors), but it's currently not possible to save mappings to MeSH. The API returns an error 500 message: "failed to detect URI: http://id.nlm.nih.gov/mesh/D001692"

https://coli-conc.gbv.de/cocoda/dev/?fromScheme=http%3A%2F%2Fbartoc.org%2Fen%2Fnode%2F1940&toScheme=http%3A%2F%2Fid.nlm.nih.gov%2Fmesh&from=http%3A%2F%2Fwww.wikidata.org%2Fentity%2FQ1435575&to=http%3A%2F%2Fid.nlm.nih.gov%2Fmesh%2FD001692&mapping=%7B%22from%22%3A%7B%22memberSet%22%3A%5B%7B%22uri%22%3A%22http%3A%2F%2Fwww.wikidata.org%2Fentity%2FQ1435575%22%7D%5D%7D,%22to%22%3A%7B%22memberSet%22%3A%5B%7B%22uri%22%3A%22http%3A%2F%2Fid.nlm.nih.gov%2Fmesh%2FD001692%22%7D%5D%7D,%22fromScheme%22%3A%7B%22uri%22%3A%22http%3A%2F%2Fbartoc.org%2Fen%2Fnode%2F1940%22%7D,%22toScheme%22%3A%7B%22uri%22%3A%22http%3A%2F%2Fid.nlm.nih.gov%2Fmesh%22%7D,%22creator%22%3A%5B%7B%22uri%22%3A%22https%3A%2F%2Fgithub.com%2Fstefandesu%22,%22prefLabel%22%3A%7B%22en%22%3A%22Stefan%20Peters%22%7D%7D%5D,%22type%22%3A%5B%22http%3A%2F%2Fwww.w3.org%2F2004%2F02%2Fskos%2Fcore%23exactMatch%22%5D,%22identifier%22%3A%5B%22urn%3Ajskos%3Amapping%3Acontent%3A12d5b6fa2416f5f7ade54f38534614a68ac126ec%22,%22urn%3Ajskos%3Amapping%3Amembers%3Ac33b0973ae259a07aeedc3562be604e3a05463bb%22%5D%7D